Month: October 2008

The potentials of Organic Pesticides

The potentials of Organic pesticides

By: O.Q. Ballesteros

Greenfields March 1993

Because of the high toxicity of chemical pesticides, alternative pest control methods should be explored.

Everyone agrees that chemical pesticides are necessary evil. We need these chemical compounds to protect our crops from pest. For instance, in irrigated rice fields that are not protected with pesticides, the insect pest damage could go up to as high it could. 

As far as unwanted plant or weeds are concerned, the estimated yield reduction is 34 percent in transplanted rice, 40 percent in direct-seeded, rainfall lowland rice; and 67 percent in upland rice.

The pesticide market.

Because of the importance of pesticides in crop production, the sale of synthetic or chemical pesticides increased yearly from 1977 to 1991, according to the Agricultural Pesticide Institute of the Philippines or APIP. In 1977, the total sale of insecticides, herbicides, fungicides and other “icides” amounted to 252.3 million pesos. Ten years later, the total sale was more than 1.5 billion pesos.

Significantly, more than 50 percent of the insecticides and herbicides purchased by farmers went to rice protection, while 60 percent of the fungicides was used to control the diseases of vegetables and fruit crops (bananas, mangoes and pineapple). Other pesticides used included, rodenticides, miticides , molluscicides and fumigants. Except for molluscicides (chemical used to control snails in ricefields and fishponds), other “icides” are generally used to protect plantation crops like sugarcane, pineapple and bananas.

Today, there is a growing awareness of the dangers posed by chemical or inorganic pesticides to the health of people and the safety of the environment. This situation has prompted government authorities to regulate and ban the use of hardly biodegradable pesticides like the chlorinated hydrocarbons (DDT, edrin) and the tin compounds. Other toxic chemicals will ultimately be banned for agricultural use pending the use of effective substitutes that originate from organic or synthetic sources.

It must  be stressed that crop protection can be attained by other methods, including proper cultural management, use of resistant crop varieties, us of beneficial insects and predators, and more effective implementation of the integrated pest management program (IPM) emphasizes the use of existing biological control agents and resistant crop varieties as well as combinations of compatible farm management practices which include the judicious use of pesticides based on the economic threshold level. Economic threshold level (ETL) refers to the level of insect population in a certain field situation at which the cost of control would roughly equal the value of crop loss.

Proper cultural management is another method of pest control. It is intended to make the environment less favorable for pest reproduction, dispersal and survival. Among these practices are thorough land preparation, adjustment of planting dates, good water management, field sanitation, and crop rotation.

Constraints of botanical pesticides. Because of the exceedingly high toxicity of chemical pesticides, alternative pesticide sources should be explored and biologically evaluated for their efficacy and economy. Among the potential plant sources are tobacco, derris, nami, or scientifically called Dioscorea hispida, neem or Azadirachta indica, mariold, chili and other plants with pesticidal properties.

Despite the hihly effective pesticidal properties of tobacco as a source of nicotine sulfate and derris because of its rotenone content, commercial production of these compounds are still not a reality. This may be attributed to inadequate raw material supply  (especially) derris which is not generally cultivated or produce), lack of incentives to processors and lack of competitiveness with regard to product quality compared with synthetic or chemical materials. Nevertheless, it may be worthwhile to assess the commercial value of these botanical sources. Limited technology is available but it may not be areal hindrance to commercialization since it requires sometime to produce large quantities or raw materials. Hopefully, the technology could be fully established by the time the material are available.

Producing the raw materials . Government efforts to develop the countryside can trigger enormous entrepreneurial interest in the production of botanical pesticides. A non-government organization may spearhead this livelihood project by entering into contract growing arrangements with farmers. The NGO could serve as the linkage or conduit of contract growers and processors, marketers and, ultimately, users. The government may provide both technical expertise and initial financing.

With certain pesticidal crops like neem, for example, commercial production could be coordinated with agroforestry projects since the neem tree can be planted on rolling hills, on unproductive lands or areas, and on steep slopes where cultivation of cash crops would accelerate soil erosion. The neem tree does not require much water. In fact, it is not advisable to plant it in waterlogged areas.

All parts of the neem tree are sources of pesticides , but the seed is the richest source, followed by the leaves, then the bark and finally the wood. It takes three to four years from germination to flowering. The tree flowers twice a year, i.e. March and September. The seeds can be harvested from June to July or four to five months after flowering. AN average tree can produce as much as 350 kilogram of green leaves annually and about 50 kilograms of fruit. From 50 kilograms of fruit about 30 kilograms of seeds and 60 % are recoverable. The 30 kilograms of oil could be extracted and 24 to 27 could be made into neem cake.

Neem extracts from leaves and fruits have strong insect repellant properties. Oil from the seed can repel termites and nematodes. It also affects the food intake of insects and cause abnormal insect molting. Because of its various uses, neem derived pesticides can be classified as “broad spectrum.” Continue reading “The potentials of Organic Pesticides”

Guyabano production -Part 2

Guyabano or soursop production

By:Onofre Q. Ballesteros

Greenfields March 1993

 Fertilization

For basal fertilization, apply five kilograms of chicken manure or other organic matter, plus 100 grams of 14-14-14 per hole. Mix the fertilizer with surface soil before setting the seedlings.

Depending on soil structure and availability of soil moisture, subsequent fertilization should be on a quarterly or semi-annual basis, 1.e. at the onset of the rainy season and before the dry season starts. Clayey soil needs less frequent application of fertilizer than light or sandy soil.

To enhance rapid vegetative growth and profuse root development, apply a mixture of urea and 14-14-14. The amount of fertilizer depends on age of trees and native soil fertility. For non-bearing trees, 300 to 500 grams of urea per tree per year is recommended. For newly bearing trees, application may range from 750 grams to 1.0 kilogram of 14-14-14 plus 200 to 500 grams of muriate of potash (0-0-60) per tree per year. The use of potash will improve fruit quality. These rates should be increased as the trees become more productive and grow older.

The fertilizer should be applied in holes dug around the base of the trees where most of the feeding roots abound. Cover the fertilizer with soil to prevent loss through volatilization and water run-off.

Pruning

Remove water sprouts and interlacing branches and prune diseased branches. Protect the cut ends by painting with coal tar, paint or pesticide paste to prevent the entry of disease organisms.

Cultivation and weeding

Shallow-plow the soil to suppress weed growth and prevent brush fires during the dry months. Remove unwanted plants growing around the trees; such plants compete with the trees for nutrients and moisture.

Mulching

The enormous quantities of organic matter produced in most farms make mulching necessary. Mulching is putting of partially, decomposed farm wastes like rice hull, straw, grass and other materials around the base of trees. Mulch conserves moisture and hinders weed growth. Mulching materials that decompose become organic matter which provides small amounts of plant food to the trees; mulch also improves soil structure.

Pest and disease management

Guyabano is attacked by scales, mealybugs, mites, nest-building ants and twig borers. Regularly spraying pesticides can control these pests. Common diseases- such as antracnose and pink disease – can be minimized by practicing sanitation and spraying the trees with fungicides like manzate, Dithane, copper and sulfur based chemicals. The grower should immediately remove and burn diseased tree parts to prevent the spread of diseases.

Maturity indices

The fruits are mature when their skins turn shiny green and the spines are set far apart. The fruits are ripe when they turn slightly yellow.

Fruiting season

Bearing trees start flowering in May and June . A second flowering occurs in November and December. Fruits may be  harvested four months after flowering/

Harvesting

Gather fully mature but still hard fruits and place them in plastic crates or bamboo baskets. Line the sides of the baskets with newspaper to protect the fruits from bruises.

Guyabano production -Part 1

Guyabano or soursop production

By:Onofre Q. Ballesteros

Greenfields March 1993

The increasing preference of health-conscious consumer for non-carbonated drinks has brought more attention to drinks made from tropical fruits like guyabano or soursop. Soursop pulp or meat contains about 80% water; one percent protein; 18 % carbohydrates and small quantities o vitamin B1, B2 and C. Ripe guyabano fruits can be eaten fresh or processed into pureeand dehydrated products. Fruits for processing into puree must be fully mature, ripe and free of bruises. Good quality flesh is white, cottony in texture, and juicy.

Soursop or guyabano is scientifically known as Anona muricata. It belongs to the Anonaceae family and is believed to have originated from tropical America. Other fruit trees belonging to this family are the sugar apple or atis (Anonas squamosa), anonas or custard apple (Anona reticulata), cherimoya (Anona cherimolia) and hybrid between cherimoya and atis known as atemoya.

Guyabano is generally grown as a backyard crop. The area devoted to it averaed 3,0816.6 hectares from 1980 to 1985. Western Visayas had the biggest hectare (740) , followed by Central Luzon (518). The average Philippine production during the same period was 3.31 tons per hectare. Average total production per year was 10,200 tons worth about 8.6 million pesos

Adaptation

Guyabano thrives in a wide range of soil types with a pH ranging from 4.3 to 8.0  Well-drained soil with high organic matter content is highly desirable.

Acidic soil (pH 4.3 to 5.5) is not conducive to good growth because of the toxic effects of acid producing  elements  like aluminum, iron and manganese.

Soil acidity can be corrected by the application of lime. Agricultural lime can be used but it takes more quantity and a longer time to effect change, unlike hydrated lime or quick lime.

Frequency of lime application depends on the acidity of the soil, soil texture, and extent of crop removal of calcium and magnesium.

Guyabano needs a warm, dry climate during its flowering period. Such a climate favors good fruit set formation as it is generally as cross-pollinated tree. Adequate soil moisture, however, is required for good fruit development. It takes about four months from flowering until fruit maturity.

Guyabano  cultivars

Based on fruit taste, there are two strains – sweet and sour . They  are botanically similar. Both grow up to seven meters tall. The leaves are alternative oval, pointed at both ends smooth and shiny, seven to 20 centimeters long, and with very short petioles. The flowers are large, heart-shaped, and yellowish or greenish yellow.

Propagation

Guyabano is generally propagated by seeds selected from fully mature fruits. A good-sized fruit mature fruits. A good-sized fruits weighs at least 750 grams and consists of94 percent pulp or meat; 11 percent peel; two percent core and three percent seeds. Seeds from 14 selected fruits are needed to plant one hectare wit a plant population of 625 trees.

Guyabano may also be propagate asexually, but it’s not common practice because trees grown from seed – sexual propagation – start flowering three years after planting.

In Guimaras, we had seedlings that started bearing 18 months after outplanting. When transplanted, the seedlings were six months old.

Asexually propagated trees, therefore, have no distinct advantage over sexually grown seedlings. The seeds should be sown in seedboxes or seedbeds. Seedlins that grow at least four leaves should be transferred to plastic bags. The soil medium for the bags should consist of sterilized loam soil and organic matter. Water the seedlings at least once a day during hot days.

Two to three weeks after you transfer the seedlings, apply a fertilizer solution every four days to accelerate plant growth and root development. Dissolve 100 grams of 14-14-14 per 17 liters of water and use this solution to water the seedlings. It is best to apply the solution at the base of the seedlings to avoid injuring young leaves. Two weeks before outplanting, reduce watering and expose the seedlings to sunlight to harden them.

Land preparation

Clear the field bu underbrushng and plowing. Allow the weeds to decompose before harrowing. Two or more harrowings are needed to thoroughly prepare  the land. Provide drainage canals or make contours if the field is slightly rolling to avert soil erosion. Dig holes measuring 2 x 2 x 2  feet and refill with surface soil and organic matter.

Spacing and outplanting

A 4 x 4 meter spacing scheme – or 625 trees per hectare – is suggested for light-texture soils. Wider spacing is recommended for clayey soil. Outplant at the start of the rainy season to give the seedlings time to develop good root systems before the dry months. Remove the plastic bags before setting the seedlings in the holes.